org.opentripplanner.analyst

Class Histogram

java.lang.Object

org.opentripplanner.analyst.Histogram

All Implemented Interfaces:

Serializable

public class Histogram
extends Object
implements Serializable

A pair of parallel histograms representing how many features are located at each amount of travel time away from from a single origin. One array contains the raw counts of features (e.g. number of places of employment M minutes from home) and the other array contains the weighted sums of those features accounting for their magnitudes (e.g. the number of jobs in all places of employment M minutes away from home). All time values are rounded down into 1-minute bins (0-60 seconds = minute 0, 61-120 = min 1, etc.)

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
int[]	counts The number features that can be reached within each one-minute bin.
static double	LOGISTIC_STEEPNESS
int[]	sums The weighted sum of all features that can be reached within each one-minute bin.
static WeightingFunction	weightingFunction The weighting functions to be used, as an array.

Constructor Summary

Constructors

Constructor and Description
Histogram() no-arg constructor for serialization/deserialization
Histogram(int[] times, int[] weight) Given parallel arrays of travel times and magnitudes for any number of destination features, construct histograms that represent the distribution of individual features and total opportunities as a function of travel time.

Method Summary

Modifier and Type	Method and Description
static Map<String,Histogram>	buildAll(int[] times, PointSet targets)
void	writeJson(com.fasterxml.jackson.core.JsonGenerator jgen) Serialize this pair of histograms out as a JSON document using the given JsonGenerator.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOGISTIC_STEEPNESS

public static final double LOGISTIC_STEEPNESS

See Also:

Constant Field Values

weightingFunction

public static WeightingFunction weightingFunction

The weighting functions to be used, as an array. Generally this will be an array of 120 functions, one to calculate cumulative accessibility for each minute in two hours. But any additive function can be used, and the output of the functions will be places in counts and sums parallel to this array.

counts

public int[] counts

The number features that can be reached within each one-minute bin. Index 0 is 0-1 minutes, index 50 is 50-51 minutes, etc. The features are not weighted by their magnitudes, so values represent (for example) the number of places of employment that can be reached rather than the total number of jobs in all those places of employment.

sums

public int[] sums

The weighted sum of all features that can be reached within each one-minute bin. Index 0 is 0-1 minutes, index 50 is 50-51 minutes, etc. Features are weighted by their magnitudes, so values represent (for example) the total number of jobs in all accessible places of employment, rather than the number of places of employment.

Constructor Detail

Histogram

public Histogram(int[] times,
                 int[] weight)

Given parallel arrays of travel times and magnitudes for any number of destination features, construct histograms that represent the distribution of individual features and total opportunities as a function of travel time. The length of the arrays containing these histograms will be equal to the maximum travel time specified in the original search request, in minutes.

Parameters:

times - the time at which each destination is reached. The array will be destructively sorted in place.

weight - the weight or magnitude of each destination reached. it is parallel to times.

Histogram

public Histogram()

no-arg constructor for serialization/deserialization

Method Detail

buildAll

public static Map<String,Histogram> buildAll(int[] times,
                                             PointSet targets)

writeJson

public void writeJson(com.fasterxml.jackson.core.JsonGenerator jgen)
               throws com.fasterxml.jackson.core.JsonGenerationException,
                      IOException

Serialize this pair of histograms out as a JSON document using the given JsonGenerator. The format is:

 {
   sums: [],
   counts: []     
 } 

Throws:

com.fasterxml.jackson.core.JsonGenerationException

IOException